Major Roy Franklin was a British Army officer who served during World War II, and also worked with Keith Mallory on numerous top-secret missions. He was Commodore Jensen's original choice to lead the British commando team to destroy the German gun emplacement on Navarone. He was close friends with Mallory and Jensen as well as explosives expert for the mission, Corporal Miller, who all knew him by his affectionate nickname "Lucky."
He was a capable leader, however during the climb up the cliffs to gain entry to the island, Franklin slipped and broke his leg. Badly hurt, he had to turn over leadership of the team to Mallory. The team debated what to do with him, whether to leave him for the Germans to find and take care of, or, fearful he might give away their plans under interrogating, to simply shoot him. While Mallory wrestled with what to do, the injured Franklin was carried around on a makeshift stretcher. Feeling like he was a burden to his friends, he tried to commit suicide, but was stopped by Mallory, who lied and told him their mission had been cancelled.
When the group took Franklin to the town of Mandrakos to get a doctor for Franklin, they were captured by Lieutenant Muesel. After escaping, they were forced to leave Franklin behind, with Muesel's assurances he'd be treated fairly. However, SS officer Captain Sessler tortured Franklin, and he was ultimately injected with a truth drug, which, it turned out, was all part of Mallory's plan. Under the influence of the drug, Franklin told the Germans the inaccurate information that the mission to destroy the guns was cancelled, and so the gun fortress was largely unguarded when Mallory and Miller sneaked in to blow them up.
After this, Franklin was given over to German civilian doctors, and treated for his injured leg in a hospital on the island. When the guns were destroyed, he and his caretakers could see the explosion from his room, and Franklin rejoiced. His fate after this is unknown.